Insulate Garage Ceiling With Foam Board and How to Do It Properly

Many homeowners choose to insulate their garage ceiling with foam board, and rigid insulation to protect the area from moisture or seepage.

This added insulation is particularly beneficial for garages that are used as living spaces or have a room above the garage, as it helps maintain a comfortable temperature and reduces the need for excessive heating or air conditioning.

This insulation material is particularly effective for existing concrete block structures, offering a barrier against external elements.

When you insulate your garage, you want to make sure that the interior isn’t exposed to cold air while maintaining the already warm air inside for a longer time at the same time.

While foam board insulation is popular, exploring other insulation materials, such as spray foam insulation and cellulose insulation, is important.

These types of insulation can offer different benefits, especially in garages that double as living spaces or have a room above the garage, where maintaining a consistent temperature is crucial. Each type of insulation offers unique benefits, especially for specific areas like the room above the garage.

How to Install Foam Board Insulation Ceiling

The foam board insulation, a rigid insulation, is ideal for insulating an existing construction, such as a garage with a room above it. This form of insulation can fit snugly between the structural elements, providing effective thermal resistance and enhancing the comfort of the living spaces above.

This type of insulation is ideal for upgrading the garage ceiling when the interior portion is already built up, ensuring it fits snugly between the structural elements.

insulate garage ceiling with foam board

You can attach the foam board through insulation addition (as well as the air seal) with these steps:

  • Install the (rigid) foam sheathing insulation on the existing garage ceiling’s underside. This kind of construction usually has a finished surface (of plaster and lath or gypsum board), where you can ‘attach’ the board. Another possible way is to attach the foam board on the ceiling joists’ underside. Still, this method only applies when your garage has its own unfinished ceiling with the joist cavities being exposed.
  • When the joist cavities are completely exposed, the insulating sheathing layer would be detailed (to serve) because of the foam’s air control layer with the taped (or caulked) edges and taped seams.
  • You can install blocking to re-install the existing attachments or services on your ceiling.

Read also: 4 Recommendations of Best Adhesive for Foam Board to Concrete

In the most detailed steps, it’s crucial to understand the ‘anatomy’ of the foam board, a common type of rigid insulation. This understanding is essential when insulating areas like a garage ceiling, especially if it impacts living spaces or a room above the garage, where the right type of insulation can make a significant difference in comfort and energy efficiency.

It often has a foil side, known as a radiant barrier, whose function is to keep the building or area warm, particularly effective in garages with a room above.

When properly used, it can help eliminate heat load coming into the building from the outside, especially from the roof deck or walls.

Read also: How to Attach Rigid Foam Insulation

If you want the radiant work to function fully, ensure an air gap between the roof deck (or wall) and the foil.

  • If you press that foil side against your wall (the foil facing outward), the radiant work won’t work but the insulation will. You reduce the conductive heat entering the building, but not so much with the radiative heat load.
  • If you use something to create the gap (between the insulation board and wall) with the foil face out, you have your own radiant barrier. In this manner, both your insulation and radiant barrier work perfectly.
  • If you install the foam board with the foil going inward, you keep the warmth within the building.

Cost to Insulate Garage Ceiling

The location where you want to install the insulation will determine the cost. The more complicated the job is, the more money should be expected. Let’s say that you want to insulate the garage doors. You ‘only’ need to pay from $500 to $700. If you want to insulate the floor, expect to spend between $600 and $900.

When you want to insulate the ceiling, expect to spend between $260 and $3,000. The walls are the costliest, ranging from $790 to $9,000.

Insulate Garage Ceiling With Foam Board of Different Types

Besides foam board, other ceiling insulation types include fiberglass, cellulose insulation, and spray foam insulation. Each type offers unique benefits for insulating a garage ceiling, particularly when considering the impact on living spaces or a room above the garage.

Choosing the right insulation material can significantly enhance these areas’ overall comfort and energy efficiency.

Each type of insulation has its own advantages, making it suitable for different applications, such as insulating the room above the garage or the garage ceiling itself.

  • Fiberglass is quite popular and common. It’s easy and inexpensive, but it’s moisture-sensitive
  • Cellulose, which is perfect for holes and cavities. It’s fire-resistant and eco-friendly, but it’s costly, and it needs drywall.
  • Spray foam, which is energy efficient and high-end. It’s mold, insect-resistant, and airtight but expensive and requires professional help.

Make sure that you pick the right one before you install everything. It’s best to consult a professional service before starting the project.

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Insulator is a skilled author and Insulation expert with years of experience in the field. He has authored several articles and books on various aspects of insulation installation, maintenance, and repair.